ABSTRACT
To evaluate the tolerability and efficacy of specific immunotherapy with mite extracts, we performed a double-blind, placebo-controlled immunotherapy study in 30 patients with proven allergy to mite allergens. The specific immunotherapy with standardized extracts of Dermatophagoides pteronyssinus and D. farinae by a clustered rush protocol was well tolerated. After 1 year of treatment, the actively treated group showed a significant improvement compared to their starting value as well as to the placebo-treated patients with regard to skin prick test, conjunctival provocation test, and subjective rhinitis score. The subjective asthma score and bronchial hyperreactivity, measured by the methacholine provocation test, was improved in comparison to the starting value, but not to the placebo group, after 12 months. However, a further, open comparison of the placebo- and verum-treated groups at 18 months revealed a significant reduction. The drug intake was not increased in the verum-treated group. Exposure to mite levels was constant throughout this time period, as revealed by antigen measurement. We conclude that specific immunotherapy in perennial, mite-allergen-induced asthma may reduce not only immediate, IgE-mediated symptoms but, after a rather long time period of 12-18 months, also the inflammatory component of bronchial asthma, thus leading to a reduction of unspecific hyperreactivity.
Subject(s)
Bronchial Hyperreactivity/therapy , Mites/immunology , Adult , Animals , Double-Blind Method , Female , Humans , Immunotherapy , Male , Middle AgedABSTRACT
Screening a human T lymphocyte cDNA library with a phosphodiesterase (PDE) specific probe resulted in the isolation of two overlapping cDNA clones, h2.2 and h6.1, that encode a type IV, rolipram inhibited cAMP-specific PDE. Clones h2.2 and h6.1 were 1015 bp and 2288 bp in length, respectively, and overlapped for 984 bp with only one nucleotide difference. The h6.1 cDNA was extended at the 5'-end by 1304 bp, with respect to h2.2, and encoded an incomplete ORF (lacking an initiation codon) of 668 amino acids. The merged nucleotide sequence of h6.1/h2.2 exhibited 99.5% homology in the ORF (ten nucleotide changes resulting in six amino acid changes), and 95% homology in the 3'-untranslated region, with the previously reported human PDE-IVA cDNA [Livi G. P., Kmetz P., Mchale M. M., Cieslinski L. B., Sathe G. M., Taylor D. P., Davis R. L., Torphy T. J. and Balcarek J. M. (1990) Mol. Cell Biol. 10, 2678-2686]. The sequence reported for h6.1/h2.2 matched that found for IVA clones isolated from three other human cDNA libraries, a human genomic cosmid clone and pcr amplified products of the exon covering these differences in two individuals. The h6.1 cDNA was engineered to generate a complete ORF by building in the 56 bp, including the initiation codon, present in hPDE-IVA-Livi and missing from the 5'-end of h6.1, producing a cognate ORF encoding a protein of 687 amino acids but differing in five amino acids which lay in or adjacent to the putative catalytic domain. The complete h6.1 ORF was engineered for expression in both Saccharomyces cerevisiae and in COS-1 cells. Integration of a single copy of the engineered ORF of h6.1, under the transcriptional control of a constitutive yeast promoter, at the pep4 locus of a S. cerevisiae strain lacking both yeast PDE genes resulted in functional complementation of the yeast pde-phenotype. Yeast strains with functional PDE were a light creamy white colour, while strains devoid of PDE activity were a dull brown colour. Expression of h6.1 in COS-1 cells led to the production of a typical type IV PDE activity in that cAMP, but not cGMP, served as substrate and its activity was insensitive to either Ca2+/CaM or cGMP but was inhibited by low concentrations of rolipram.(ABSTRACT TRUNCATED AT 400 WORDS)
